As an example of ROIs implemented in a moving picture codec, there are H.263-based encoding and an MPEG-4 object-based encoding. An independent segment decoding (ISO) mode which provides a method of independently decoding a specific region in the H.263 is the same as the MPEG-4 object-based encoding from the point of view that the region that is to-be-independently decoded is treated as one full image in the encoding. However, the ISD mode is different from the MPEG-4 object-based encoding as follows.
1. ISD Mode in H.263
In H.263-based encoding, a method of independently decoding a specific region in an image is provided as an option (see Annex R of H.263). In particular, in the H.263-based encoding, spatial, temporal, and quality scalabilities can be provided by using scalable hierarchical coding.
In the H.263, the quality scalability is provided by using a method corresponding to coarse grain scalability (CGS) of SVC, and the temporal scalability is provided by using a method corresponding to fine grain scalability (FGS) and supporting a variable frame. In addition, in the case of the spatial scalability, similarly to scalable video decoding (SVD), coding is performed in terms of resolutions, and inter-layer coding is performed by using an image having a lower resolution.
2. MPEG-4 Object-Based Coder
In the MPEG-4 object-based coding, an object region having an arbitrary form is coded into a rectangular region defined by a video object plane (VOP). According to this method, similar to the ROI, a specific region in an image is coded in such a way that it can be independently decoded.
The SVC based on the H.264-based encoding has a higher coding rate than H.263 and MPEG-4, and a coding scheme in the SVC is different from those of H.263 and MPEG-4.